An estimated 40,000 manufactured products contain latex. With
increased use has come increased allergies. Here's what to look for
and how to avoid problems.

An estimated 40,000 products, used billions of times each year,
contain natural rubber latex.[1] As health care workers, we come in
contact with latex every day, whether it be through gloves, catheters,
intubation tubes, anesthesia masks, blood pressure cuffs, adhesive tape,
or tourniquets, just to name a few sources.

Furthermore, there are many latex products commonly found in the
home, including pacifiers, balloons, condoms, rubber bands, bails, and
toys. See "Harvesting Hevea brasiliensis" on the next page for
an explanation of the origin and manufacture of latex products.

* Occupational allergy. The use of latex gloves has grown
dramatically due to the increased awareness of AIDS, implementation of
universal precautions, and enforcement of other OSHA regulations. This
boom in the use of latex products has led to increased reports of latex
allergy.

In addition to health care professionals, other groups seem to be at
higher risk for latex sensitivity. One of these groups is children with
spinal cord injuries such as spina bifida. A 1989 study showed that 10
out of 12 spina bifida patients have severe reactions to latex.[2] These
patients undergo multiple surgeries and frequent bladder
catheterization, increasing their exposure to latex products.

Latex allergy has been well documented. While the incidence of latex
allergy is [less than] 1% in the general nonatopic population,[3]
reported cases are highest in patients who undergo multiple surgical
procedures, including those with spina bifida, followed by dentists,
surgical personnel, and other hospital employees (see Figure 1).

* Severe reactions. On March 29, 1991, the FDA issued a medical alert
titled "Allergic Reactions to Latex-Containing Medical
Devices."[4] The purpose of the alert was to advise health care
workers to be aware of latex allergy and to be prepared to treat
attendant reactions promptly. This alert was based on reports of severe
allergic reactions to common latex-containing medical devices. The FDA
has also published data on the incidence of anaphylactic reactions to
several different products containing latex, several of which are listed
in Figure 2.

Another cause of increased latex allergy was lack of QC guidelines in
glove manufacturing in the mid- to late '80s.[5] With greater
demand for latex gloves, many inexperienced manufacturers sacrificed
quality for profit, resulting in the manufacture and sale of poor
quality gloves containing many potential allergens.

* Highest risk. Latex allergies result from repeated exposure to
latex products; sensitization occurs over a long period of time. Latex
allergens enter the body through inhalation or by way of cuts or open
sores on the hands. Dry, chapped hands, resulting from cold weather or
using alcohols and soaps, are common routes of entry.[6]

Patients allergic to latex are at greatest risk for anaphylaxis when
there is direct contact between latex and mucosal surfaces. Latex
proteins bind to glove starch.[7] Patient contact occurs when glove
powder bound with latex proteins, water soluble proteins, and chemicals
is transferred from the latex device to patient tissue (in surgery,
e.g.). This results in direct inoculation of the antigen, which leads to
an IgE-mediated antibody response. Sensitization via glove powders bound
with latex protein may cause asthma, allergic rhinitis, sinus problems,
or systemic manifestations.[8]

* Types of reactions. There are three major types of reactions to
latex: contact dermatitis and types IV and I hypersensitivities.

Contact dermatitis is the most common type of reaction. This is not
an allergic reaction involving the immune system, but rather a skin
irritation caused by the chemicals added to the latex during
manufacturing or by the glove powder itself.[9]

Type IV delayed hyper-sensitivity is the second most common type of
latex allergy. This reaction is mediated by T-cells and is characterized
by burning, swelling, and the development of debilitating rashes with
itching and cracking of the hands. This type of hypersensitivity is also
believed to be caused by sensitization to those chemicals added to latex
during the manufacturing process.[10] The type IV reaction is comparable
to the allergic contact dermatitis caused by poison ivy.

Type I immediate hypersensitivity is the least common and the most
serious reaction, one that can be life-threatening. The response is an
IgE-mediated anaphylaxis that induces the body to manufacture potent
chemical mediators that produce such symptoms as hypotension, urticaria,
edema, nausea, vomiting, diarrhea, sneezing, and nasal congestion.[11]
Type I immediate hypersensitivity is an immune response to a foreign
substance (the latex protein) characterized by the synthesis of IgE,
which has a high affinity for mast cells and basophils. When the skin or
mucous membranes are reexposed to the allergen(s), IgE bound to the
receptors on the surface of the aforementioned cells causes them to
degranulate and release histamine, pros-taglandin, leukotrienes,
etc.[12]

The presence of latex antigen triggers a cellular response, with
subsequent sensitization and antibody production by lymphocytes. The
response to latex is shown to be IgE mediated through skin testing,
basophil histamine release, RAST, ELISA, and IgE immunoblot.[13,14]

* What's being done? At the present time, researchers and
manufacturers of latex products are developing new techniques to remove
the offending allergens during manufacture. Low-allergen latex gloves
are on the market.[15] Different washing techniques remove latex
proteins and maintain a product that has tensile strength and barrier
protection. Protein levels are being monitored using protein assays,
ELISA, RAST-inhibition, and nesslerization.[16] Makers of latex products
continue to maintain lower levels of protein.

What do we do to reduce the risk? The first step is to be aware of
the potential dangers of latex allergy. Be alert to the threat of latex
allergy and latex-induced anaphylaxis, especially in patients who have
had multiple surgeries. All patients, regardless of risk group, should
be questioned about a history of latex allergy. We must work hard to
provide a latex-free environment for all latex-sensitive patients.[17]

* Life without latex. A latex-free environment includes using
nonlatex gloves, catheters, endotracheal tubes, suction tubing, and
other such implements. Avoid latex bandages, tourniquets, and blood
pressure cuffs. When taking blood from a latex-sensitive patient, wear
non-latex gloves and don't take trays of supplies into
patients' rooms. Use a cloth tourniquet and latex-free tape/gauze
in lieu of latex bandages to help prevent transmission of aerosolized antigens.

Health care workers sensitive to latex should use nonlatex gloves
such as those made of polyvinyl chloride or neoprene. These gloves do
not provide optimal barrier protection against the transmission of
viruses, however. If you do wear latex gloves, limit exposure to its
allergens by routinely washing your hands, and avoid touching eyes,
nose, or mouth to prevent direct contact with mucous membranes.

Do not use petroleum products or other skin protectants when wearing
latex gloves. These substances break down the latex and decrease barrier
integrity. Routine use has the same effect.[18] The FDA has suggested
wearing a latex glove between two vinyl gloves.[4] If a latex allergy
develops, notify your personal health care provider and follow his/her
suggestions regarding precautions.

Natural rubber latex is a product of the rubber tree Hevea
brasiliensis, which originated in the Amazon. Most of today's
rubber tree plantations are located in Malaysia, Indonesia, and
Thailand, however.

Rubber trees must grow from 6 to 8 years before they are ready to
harvest but then can produce latex for up to 28 years. One tree will
produce approximately 10 pairs of surgical gloves each week.[1] The
milky sap (latex) contains about 30% rubber, 65% water, 1.8% protein,
and 2% resin. Rubber particles are coated with phospholipids and protein
to help provide stability and prevent the latex from coagulating.[2]

If steps are not taken to stabilize the natural rubber, it
spontaneously coagulates within the first few hours after collection due
to microbial attack on the nonrubber constituents and the hydrolysis of
protein.[2] The most widely used, method of preserving latex is adding
ammonia, which helps prevent microbial attachment.

During manufacturing, many chemicals are added to the latex,
including vulcanizers, accelerators, stabilizers, and antioxidants.[2]
The exact mixture and process varies, depending on the physical
properties needed for the application of the rubber. Each formulation of
latex is designed to produce a product with the appropriate tensile
strength and, if needed, barrier protection.

Christine D. Personius, MT(ASCP), CLS(NCA) is a medical technologist
at Robert Packer Hospital in Sayre, Pa. Before that she was research
technician on a project investigating latex allergies, conducted at the
Donald Guthrie Medical Research Foundation, also in Sayre. She thanks
Carol Camp, Terrie Zimmer, and Donald Beezhold for their time and effort
in reviewing this article.

COPYRIGHT 1995 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.